1. Field of the Invention
The present invention relates to a digital communication system comprising at least one primary station arranged for frequency hopping based burst mode communication with a plurality of secondary stations, the primary station comprising a plurality of transceivers and a plurality of transceiver controllers which are coupled to the transceivers via a distribution medium. Such a system can be a digital cellular radio system in which the primary station is a radio base station and the secondary stations are mobile radio stations, or any other frequency hopping based digital communication system.
The present invention further relates to a primary station for use in such a system.
2. Description of the Related Art
A digital communication system and primary station of this kind are known from the International Patent Application WO 90/16122. In this Patent Application a radio base station for use in TDMA (Time Division Multiple Access) digital mobile radio systems is disclosed using frequency hopping techniques. The base station comprises a plurality of transceivers which are coupled to at least one antenna via a so-called combiner, and further a base station controller and a plurality of transceiver controllers. The transceiver controllers comprise channel codecs, speech codecs, and processors for handling signalling data or the like. For efficiently implementing a so-called baseband switching frequency hopping technique, the transceivers and the transceiver controller are coupled to a bus as a common distribution medium, the bus also being coupled to the base station controller. The transceiver comprises a receiver for receiving data such as voice data or other data from mobile stations and a transmitter for transmitting data to the mobile stations on a TDMA basis. Via the bus, when receiving, for particular mobile subscribers time slots e.g. containing bursts of digitally coded speech are directed to the correct transceiver controller as determined by a frequency hopping algorithm comprised in the base station controller, i.e. on a TDMA frame basis, each transceiver is connected with the correct transceiver controller. When transmitting a similar approach is taken. With baseband switching frequency hopping, the transceivers are tuned to fixed frequencies, the TDMA bursts to and from particular mobile subscribers having varying time slot positions within the TDMA frames. Such a bus structure as a common distribution medium is disadvantageous as to fault tolerance of the system. For a fault tolerant system, the bus should be doubled (redundancy).